我正在尝试使用wtforms在flask中创建下拉列表，但由于某种原因我的表单无法验证，有人可以告诉我为什么吗？

问题描述

这些列表看起来和我想要的一样，具有所有正确的选项，但是当我按下Submit（'Add Movement'）按钮时，它没有得到验证（它没有输入{{1 }}代码块）。在我添加SelectField之前，它曾经得到过验证，因此我倾向于认为我在这里做错了。

if form.validate_on_submit()

这是我的“运动”表模型：

@app.route('/movements',methods=['GET','POST'])
def movements():
    form = MovementForm()
    if form.validate_on_submit():
        product = Product.query.filter_by(id=form.product.data).first()
        from_location = Location.query.filter_by(id=form.from_location.data).first()
        to_location = Location.query.filter_by(id=form.to_location.data).first()
        m = Movement(product = product.name,from_location = from_location.name,to_location = to_location.name,quantity = form.quantity.data)
        db.session.add(m)
        db.session.commit()
        movements = Movement.query.all()
        products = Product.query.all()
        locations = Location.query.all()
        return render_template('movements.html',movements=movements,products=products,locations=locations,form=form)
    
    form.product.choices = [(product.id,product.name) for product in Product.query.all()]
    form.from_location.choices = [(location.id,location.name) for location in Location.query.all()]
    form.to_location.choices = [(location.id,location.name) for location in Location.query.all()]
    movements = Movement.query.all()
    products = Product.query.all()
    locations = Location.query.all()
    return render_template('movements.html',form=form)

这是表格：

class Movement(db.Model):
    id = db.Column(db.Integer,primary_key=True)
    product_id = db.Column(db.Integer,db.ForeignKey('product.id'))
    product = db.Column(db.String(50),nullable=False)
    from_location_id = db.Column(db.Integer,db.ForeignKey('location.id'))
    from_location = db.Column(db.String(50))
    to_location_id = db.Column(db.Integer,db.ForeignKey('location.id'))
    to_location = db.Column(db.String(50))
    quantity = db.Column(db.Integer,nullable=False)
    timestamp = db.Column(db.DateTime,nullable=False,default=datetime.utcNow)

解决方法

我认为我也有类似的经历，问题是表格没有针对空的选择列表进行验证。因此，在验证之前填写form.from_location.choices（及其他）可以解决该问题：

@app.route('/movements',methods=['GET','POST'])
def movements():
    form = MovementForm()
    form.product.choices = [(product.id,product.name) for product in Product.query.all()]
    form.from_location.choices = [(location.id,location.name) for location in Location.query.all()]
    form.to_location.choices = [(location.id,location.name) for location in Location.query.all()]
    if form.validate_on_submit():
        # your code
        
    # your code
    return render_template('movements.html',movements=movements,products=products,locations=locations,form=form)